Next.js 15 App Router

Directory Structure

• app/ - Routes and API handlers
• client/ - Client components and utilities
• server/ - Server-side services
• shared/ - Shared types and utilities

Route Handlers (API)

// app/api/example/route.ts
import { NextRequest, NextResponse } from 'next/server';

export async function POST(request: NextRequest) {
  const body = await request.json();
  // Validate with zod schema from shared/validation/
  return NextResponse.json({ data });
}

Server Components (Default)

// No 'use client' directive
export default async function Page() {
  const data = await fetchData(); // Direct DB/API calls
  return <div>{data}</div>;
}

Client Components

'use client';
// Required for: hooks, browser APIs, event handlers, state
import { useState } from 'react';

Data Fetching

• Server Components: Direct async/await
• Client Components: Use client/utils/api-client.ts

Caching

// Revalidate every hour
export const revalidate = 3600;

// Or disable caching
export const dynamic = 'force-dynamic';

Error Handling

• error.tsx - Error boundary per route
• not-found.tsx - 404 handling
• loading.tsx - Suspense fallback

Metadata

export const metadata = {
  title: 'Page Title',
  description: 'Page description',
};